Merge lp:~mc-return/compiz/compiz.merge-fix1068173-grid-does-not-follow-preview into lp:compiz/0.9.9

[MC Return]

Check on which display your pointer is at, before calculating edges/corners for the snap preview.

The problem here is that detection (if the cursor enters another output) is done after the trigger edges have already been detected and calculated, so if you enter a new screen the preview will still have the old values and not follow the mousepointer to the new monitor. Then if you release the mousebutton the resize won't follow the preview, but resize correctly on the monitor your cursor is currently at, while still showing the old preview.

(LP: #1068173)

Videos are showing the situation best :)

Before the fix: https://bugs.launchpad.net/compiz/+bug/1068173/+attachment/3402754/+files/Grid-does-not-always-follow-the-preview.webm

After the fix:
https://bugs.launchpad.net/compiz/+bug/1068173/+attachment/3411964/+files/Grid-preview-always-follows-the-mousepointer-now.webm

[Sam Spilsbury (smspillaz)]

This looks fine to me, any thoughts Daniel?

review: Approve

[Daniel van Vugt (vanvugt)]

I'm not familiar with the affected code, but it looks straightforward and testing with two monitors I can confirm it fixes the bug.

review: Approve

=== modified file 'plugins/grid/src/grid.cpp'
--- plugins/grid/src/grid.cpp	2012-10-18 11:05:40 +0000
+++ plugins/grid/src/grid.cpp	2012-10-24 15:45:52 +0000
@@ -695,6 +695,23 @@
     if (event->type != MotionNotify || !mGrabWindow)
 	return;
 
+    /* Detect when cursor enters another output */
+
+    currentWorkarea = screen->getWorkareaForOutput
+			    (screen->outputDeviceForPoint (pointerX, pointerY));
+    if (lastWorkarea != currentWorkarea)
+    {
+	lastWorkarea = currentWorkarea;
+
+	if (cScreen)
+	    cScreen->damageRegion (desiredSlot);
+
+	initiateCommon (0, 0, o, typeToMask (edgeToGridType ()), false, false);
+
+	if (cScreen)
+	    cScreen->damageRegion (desiredSlot);
+    }
+
     out = screen->outputDevs ().at (
                    screen->outputDeviceForPoint (CompPoint (pointerX, pointerY)));
 
@@ -731,23 +748,6 @@
     else
 	edge = NoEdge;
 
-    /* Detect when cursor enters another output */
-
-    currentWorkarea = screen->getWorkareaForOutput
-			    (screen->outputDeviceForPoint (pointerX, pointerY));
-    if (lastWorkarea != currentWorkarea)
-    {
-	lastWorkarea = currentWorkarea;
-
-	if (cScreen)
-	    cScreen->damageRegion (desiredSlot);
-
-	initiateCommon (0, 0, o, typeToMask (edgeToGridType ()), false, false);
-
-	if (cScreen)
-	    cScreen->damageRegion (desiredSlot);
-    }
-
     /* Detect edge region change */
 
     if (lastEdge != edge)